With wide deployment(s) of flash drives being used in various environments (secured or otherwise), the issue of data and information security remains important. The use of biometrics and encryption is becoming the norm with the need for increased security for data; on-the-fly encryption systems are particularly useful in this regard, as they can transparently encrypt large amounts of data. In some cases a secure USB drive may use a hardware-based encryption mechanism that uses a hardware module instead of software for strongly encrypting data. IEEE 1667 is an attempt to create a generic authentication platform for USB drives. It is supported in Windows 7 and Windows Vista (Service Pack 2 with a hotfix).[47]
Hardware designers later developed EEPROMs with the erasure region broken up into smaller "fields" that could be erased individually without affecting the others. Altering the contents of a particular memory location involved copying the entire field into an off-chip buffer memory, erasing the field, modifying the data as required in the buffer, and re-writing it into the same field. This required considerable computer support, and PC-based EEPROM flash memory systems often carried their own dedicated microprocessor system. Flash drives are more or less a miniaturized version of this.
The development of high-speed serial data interfaces such as USB made semiconductor memory systems with serially accessed storage viable, and the simultaneous development of small, high-speed, low-power microprocessor systems allowed this to be incorporated into extremely compact systems. Serial access requires far fewer electrical connections for the memory chips than does parallel access, which has simplified the manufacture of multi-gigabyte drives.
Flash drives are often measured by the rate at which they transfer data. Transfer rates may be given in megabytes per second (MB/s), megabits per second (Mbit/s), or in optical drive multipliers such as "180X" (180 times 150 KiB/s).[19] File transfer rates vary considerably among devices. Second generation flash drives have claimed to read at up to 30 MB/s and write at about half that rate, which was about 20 times faster than the theoretical transfer rate achievable by the previous model, USB 1.1, which is limited to 12 Mbit/s (1.5 MB/s) with accounted overhead.[20] The effective transfer rate of a device is significantly affected by the data access pattern.[21]
A recent development for the use of a USB Flash Drive as an application carrier is to carry the Computer Online Forensic Evidence Extractor (COFEE) application developed by Microsoft. COFEE is a set of applications designed to search for and extract digital evidence on computers confiscated from suspects.[48] Forensic software is required not to alter, in any way, the information stored on the computer being examined. Other forensic suites run from CD-ROM or DVD-ROM, but cannot store data on the media they are run from (although they can write to other attached devices, such as external drives or memory sticks).
To ensure this information isn't stolen as well, having a locked flash drive can keep anyone from viewing your files should the drive fall into the wrong hands. Tiny and portable, they easily slip into a pants or coat pocket, in a computer bag or purse, and come in a variety of shapes and sizes. External keypads add an additional level of security to portable memory, meaning a viewer must first input a numerical code to gain access to files. These in turn can be encrypted and password protected, deterring serious threats to personal security.
Particularly with the advent of USB, external hard disks have become widely available and inexpensive. External hard disk drives currently cost less per gigabyte than flash drives and are available in larger capacities. Some hard drives support alternative and faster interfaces than USB 2.0 (e.g., Thunderbolt, FireWire and eSATA). For consecutive sector writes and reads (for example, from an unfragmented file), most hard drives can provide a much higher sustained data rate than current NAND flash memory, though mechanical latencies seriously impact hard drive performance.
Some manufacturers deploy physical authentication tokens in the form of a flash drive. These are used to control access to a sensitive system by containing encryption keys or, more commonly, communicating with security software on the target machine. The system is designed so the target machine will not operate except when the flash drive device is plugged into it. Some of these "PC lock" devices also function as normal flash drives when plugged into other machines.
Flash memory cards, e.g., Secure Digital cards, are available in various formats and capacities, and are used by many consumer devices. However, while virtually all PCs have USB ports, allowing the use of USB flash drives, memory card readers are not commonly supplied as standard equipment (particularly with desktop computers). Although inexpensive card readers are available that read many common formats, this results in two pieces of portable equipment (card plus reader) rather than one.
USB flash drives usually specify their read and write speeds in megabytes per second (MB/s); read speed is usually faster. These speeds are for optimal conditions; real-world speeds are usually slower. In particular, circumstances that often lead to speeds much lower than advertised are transfer (particularly writing) of many small files rather than a few very large ones, and mixed reading and writing to the same device.
On the more practical side our flash drives, also called thumbdrives or memory sticks are available in memory capacities from 64MB to 256GB. With memory capacities like that, we certainly have the options to cover whatever your data storage requirements may be. For more information on data storage capacities, check out our USB Flash Drive Capacity Guide.
These products use flash memory chips, a stable, high-density storage medium, to hold your data. They pack a huge amount of information into a compact form factor. Most thumb drives are less than 2 inches long and easily fit in a pocket, laptop bag or purse. Models with built-in covers protect physical connectors from damage, and select products feature rugged silicon and metal shells that enhance heat and water resistance.
